We all know that number. It’s Rafael Nadal’s record against Novak Djokovic this year, all in finals. It’s also the score of the last set of the Tokyo final, won by Andy Murray over Nadal.

This is not good, seeing as it suggests a pattern. The score of the last set of the U.S. Open final: 1-6, Nole over Rafa. Who would have ever thought that Nadal would start to go gently into the night? The one thing we always could count on with him was his willingness to spit blood, to be carried out on a stretcher. He might lose but he was going to make his conqueror feel it the next day.

OK, not so fast. Yes, Djokovic has got his number right now, but beyond that there’s really nothing to be concerned about. The fall swing, after all, has never been his strong suit. So even if he’s won his last tournament for the year, let’s not panic.

Rafael Nadal is not in decline. He won the French Open and reached the final at Wimbledon and the U.S. Open. He’ll finish up at No. 2 in the world. Not a bad 2011. The knees are fine, the psyche battered but easily repaired.

You can bet he and Uncle Toni are thinking and plotting his return to the top. He fought long and hard to overtake Roger Federer in the rankings; he’s not going to walk away from the number-one slot without a fight.

Better yet, Nadal loves to reinvent himself -- within carefully defined limits, that is. For the vast majority of players, once they break through on the top-level tour, their development is over. They do what they do, and they will win or lose with that style and skill set.

Not so Rafa. He’s always been a work in progress. He enjoys trying to improve. He enjoys trying different things. He’s learned to flatten out the ball, to step into his service return, to play at the net. His serve is entirely different from the fluff ball he hit back in 2005, when he won his first major title.

This development will continue, this time with Novak Djokovic foremost in his mind. Will he work on his backhand? On his drop shot? On his aggression?

That’s for Rafa and Toni to know and for you and I -- and Novak -- to find out.

The change, I suspect, will be subtle but definitive. And I expect it to work -- and perhaps create some unexpected consequences. I wouldn’t be surprised if Djokovic beats Nadal to win the French Open next spring, but then loses to Rafa at Wimbledon and/or the U.S. Open.

Nadal increasingly will be a fast-court player, willing and able to work out there on the ragged edge. Of course, he won’t be the only player trying to improve. Djokovic is forcing reevaluation and redevelopment on all of the top players, just as Federer forced it on Nadal a few years ago. Djokovic will be looking to continue his run; Murray will be looking to get that first major; Federer will be looking to get at least one more major.

Something’s got to give. And someone’s has to end up at the top of the heap.